Standardized ileal digestible lysine requirements based on growth performance and histochemical characteristics of male broilers from 10 to 21 d of age

Optimizing broiler growth performance through balanced net energy, standard ileal digestible lysine, and amylose/amylopectin ratios: a Box-Behnken response surface approach

This study investigated the effects of net energy (NE), standard ileal digestible lysine (SID Lys), and amylose/amylopectin (AM/AP) ratios on broiler growth performance using a Box-Behnken design. A total of 936 male Arbor Acres Plus broilers (15-35 days post-hatch) were allocated to thirteen treatments with three factors at three levels including NE (2,000, 2,250, 2,500 kcal/kg), SID Lys (1.00 %, 1.20 %, 1.40 %), and AM/AP ratios (0.17, 0.22, 0.27, composed of different ratios of pea starch and waxy corn starch). Growth performance was measured weekly. At the growth stage of 15-20 d, quadratic relationships between dietary NE (P = 0.038), SID Lys (P = 0.010), AM/AP ratios (P = 0.021), and broiler 20 d body weight (BW), with optimization occurring at 2,303 kcal/kg NE, 1.24 % SID Lys, and an AM/AP ratio of 0.22. The 15-25 d feed-to-gain ratio (F/G) decreased linearly with increasing dietary NE (P = 0.038) and SID Lys (P = 0.010). At the growth stage of 21-27 d, linear increases in broiler 27 d BW (P = 0.007) and 21-27 d body weight gain (BWG) (P = 0.013) were observed with higher dietary SID Lys levels, reaching a peak at 2,500 kcal/kg NE, 1.40 % SID Lys, and an AM/AP ratio of 0.17. The 21-27 d F/G decreased linearly with increasing dietary NE (P < 0.001) and SID Lys (P < 0.001) levels. At the 28-35 d growth stage, a significant interaction between NE and SID Lys levels was observed for 35 d BW (P = 0.016) and 28-35 d BWG (P = 0.007). At 2,500 kcal/kg NE, both 35 d BW and 28-35 d BWG increased with higher SID Lys, whereas at 2,000 kcal/kg NE, they initially increased and then decreased as SID Lys levels rose. There was a significant interaction effect of NE and AM/AP ratio on broiler 28-35 d BWG (P = 0.017). Further quadratic curve fitting of 28-35 d BWG and 15-35 d BWG against dietary SID Lys/NE ratio revealed that 28-35 d BWG and 15-35 d BWG were optimized at dietary SID Lys/NE of 5.68 and 5.80 mg/kcal, respectively. These data indicate balancing dietary NE and SID Lys can optimize broiler growth, while lowering the dietary AM/AP ratio further enhances growth performance, likely due to improved starch digestibility and energy release dynamics. This study provides actionable insights for precision nutrition strategies in broiler production.

Standardized ileal digestible lysine requirements based on growth performance of White Pekin ducks for 21 days after hatch

The purpose of this study was to assess the optimal standardized ileal digestible (SID) lysine (Lys) requirement for male White Pekin ducklings with a specific focus on growth performance for the 3 weeks following hatching. A total of 384 one-day-old male White Pekin ducklings were allocated to six different dietary treatments, each containing varying levels of digestible Lys content ranging from 0.72% to 1.12%. All amino acids in the diets remained consistent except for Lys. The ducklings were randomly distributed into 24-floor pens, with each treatment group comprising eight pens, and each pen housing eight ducklings. The diets were offered ad-libitum throughout the study. Weekly measurements of body weight and feed intake were recorded to calculate the feed conversion ratio. The SID Lys requirement was determined by analyzing the data using both linear-plateau and quadratic-plateau models and calculating the mean value. The results demonstrated a significant linear (p < 0.001) and quadratic (p < 0.001) improvement in body weight gain and feed efficiency with increasing SID Lys content in the diet. According to the linear-plateau regression analysis, the estimated SID Lys requirements for final body weight, weight gain, and feed efficiency were 1.00%, 1.00%, and 0.98%, respectively. Conversely, the quadratic-plateau regression analysis yielded estimated SID Lys requirements of 1.11%, 1.11%, and 1.10%, respectively, for the same parameters. In summary, this study established that the recommended SID Lys levels for White Pekin ducklings for the 3 wk period after hatching were found to be 1.05%, 1.05%, and 1.04% for achieving the finest final body weight, daily gain, and feed efficiency, respectively.

Estimation of Optimal and Maximum Standardized Ileal Digestible Methionine Requirements Based on Performance for Male Broilers Aged 0 to 21 Days

Two experiments were conducted with Ross 308 male broiler chickens to determine the standardized ileal digestible (SID) methionine (Met) requirement for maximum weight gain during the starter (0 to 10 days) and grower (10 to 21 days) phases. A total of 720 and 288 birds were allocated to Experiments 1 and 2, respectively, and assigned six dietary treatments in a randomized complete block design. The experimental diets were formulated with corn, soybean meal, and synthetic amino acids to achieve varying SID Met levels (3.8 to 5.8 g/kg in experiment 1 and 3.0 to 5.5 g/kg in experiment 2), with increments of 0.4 and 0.5 g/kg. Weight gain, feed intake, and the gain-to-feed ratio (G:F) increased quadratically (p < 0.05) as dietary SID Met increased. The SID Met requirements for maximum weight gain and G:F in the starter phase were 5.1 g/kg (79.5 mg/d) and 5.3 g/kg (89.8 mg/d), while in the grower phase, they were 5.5 g/kg (343.0 mg/d) and 5.4 g/kg (330.3 mg/d), respectively. These findings, divided into two growth phases, provide guidelines to facilitate the optimal and maximum performance of young male broilers, and this may facilitate the selection of appropriate values for formulating broiler feed. These findings also highlight the importance of Met supplementation strategies for improving performance.

Effects of duo-strain probiotics on growth, digestion, and gut health in broiler chickens

The goal of this inquiry was to analyze the impact of incorporating Enterococcus faecium and Streptococcus thermophilus using a novel premix-spray method on the following aspects: growth rate, digestive enzyme activity, antioxidant levels, gut microbiome composition, and the morphological characteristics of the duodenum, jejunum, and ileum in broiler chickens. Furthermore, this study explored the potential benefits of duo strains of probiotics (DSP) in reducing flatulence, regulating stool microbial population, and improving diarrhea symptoms. A total of 360 one-day-old mixed-sex Plymouth Rock chicks (IW: 51 ± 33 g) were randomly divided into two treatment groups. Each treatment group was further divided into 9 replicated cages, with 20 chicks housed in each cage. The control group (CG) received a basal diet composed of a soy-corn mixture, whereas the experimental group was provided with DSP (CON + 0.5 % probiotic). The results showed that the increase in the body weight of broilers at the end of the fourth week in the control group and the treatment group was 1.576 versus 1.847 kg, respectively. Throughout the 30-day trial period, the DSP diet significantly improved the specific growth rate (SGR), survival rate (SR), and body weight gain (BWG) while decreasing the feed conversion ratio (FCR) (P < 0.05). The DSP diet also enhanced the Enzymatic digestion (protease, amylase, lipase, and trypsin) and antioxidant potential (SOD, MDA, and catalase) of the broilers compared to those in the CG. The results revealed significant enhancements in the tissue morphology of the duodenum and jejunum following the combined treatment for a duration of 4 weeks. The DSP treatments significantly increased microvillus height in the duodenum and jejunum but had no notable effects in the ileum. Incorporating 0.5 % DSP in poultry feed improved the relative abundance of Ruminococcaceae and Faecalibacteriumin, leading to better management of diarrhea and reduced presence of E. coli compared to the control diet. Additionally, including probiotics in the basal diet reduced H2S, CO2, NH3, and CH4 levels. Overall, the study suggests that the new spray-drying approach with these strains has potential for supplementing probiotics in poultry feed processing, and including DSP in broiler chicken diets has beneficial effects.